Ear plugs; electric arc welding machines; metal cutting machines (by arc, gas or plasma); electric welding apparatus; ozonisers (ozonators); electrolysers (electrolytic cells); egg-candlers, cash registers; coin counting or sorting machines; electric sign boards for displaying target figures, current outputs or the like; photocopying machines; manually operated computing apparatus; drawing or drafting machines and apparatus; time and date stamping machines; time clocks (time recording devices...